A High-Sensitivity MEMS Accelerometer Using a Sc0.8Al0.2N-Based Four Beam Structure

Abstract

In this paper, a high-sensitivity microelectromechanical system (MEMS) piezoelectric accelerometer based on a Scandium-doped Aluminum Nitride (ScAlN) thin film is proposed. The primary structure of this accelerometer is a silicon proof mass fixed by four piezoelectric cantilever beams. In order to enhance the sensitivity of the accelerometer, the Sc0.2Al0.8N piezoelectric film is used in the device. The transverse piezoelectric coefficient d31 of the Sc0.2Al0.8N piezoelectric film is measured by the cantilever beam method and found to be −4.7661 pC/N, which is approximately two to three times greater than that of a pure AlN film. To further enhance the sensitivity of the accelerometer, the top electrodes are divided into inner and outer electrodes; then, the four piezoelectric cantilever beams can achieve a series connection by these inner and outer electrodes. Subsequently, theoretical and finite element models are established to analyze the effectiveness of the above structure. After fabricating the device, the measurement results demonstrate that the resonant frequency of the device is 7.24 kHz and the operating frequency is 56 Hz to 2360 Hz. At a frequency of 480 Hz, the sensitivity, minimum detectable acceleration, and resolution of the device are 2.448 mV/g, 1 mg, and 1 mg, respectively. The linearity of the accelerometer is good for accelerations less than 2 g. The proposed piezoelectric MEMS accelerometer has demonstrated high sensitivity and linearity, making it suitable for accurately detecting low-frequency vibrations.

High-Sensitivity Piezoelectric MEMS Accelerometer for Vector Hydrophones

“…The stress difference on the two surfaces of the cantilever beam leads to the distribution of charges between the two surfaces, as shown in Figure 2 . In this structure, there are two piezoelectric units connected in series, one lower electrode and two disconnected upper electrodes [ 31 ].…”

A Scale Factor Calibration Method for MEMS Resonant Accelerometers Based on Virtual Accelerations

“…MEMS accelerometers have been widely used in consumer electronics, industrial control, energy exploration, and aerospace fields due to their small size, low cost, low power consumption, easy integration, and massive production [ 1 , 2 ]. Compared to piezoresistive [ 3 ], piezoelectric [ 4 , 5 ], and capacitive [ 6 ] accelerometers, micromachined resonant accelerometers (MRAs) have the characteristics of high sensitivity, large dynamic range, and strong anti-interference ability [ 7 , 8 ]. Therefore, they have a good application prospect.…”